Eclipse can be slow, very slow, here's some quick steps to increase Eclipse speed.

Download the latest version of Eclipse and Java

You must upgrade to the latest version in the official Helios download page
A note of the latest version of PDT that make interesting changes, check this page to know more about them.
Upgrading Java Virtual Machine is also essential.

Eclipse PDT Configuration

Add more RAM to Eclipse

Open configuration file eclipse.ini in your Eclipse installation folder, then add more memory, and restart.